question about video streaming

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tom78
Posts: 4
Joined: Wed Apr 10, 2019 7:50 am

question about video streaming

Post by tom78 » Wed Apr 10, 2019 8:20 am

I'm using the trial evaluation of primo cache and so far i'm positively impressed.

I use primo cache to speed up an old 1 TB hard drive, where i usually install video games and I record tv streaming from an usb video tuner.

The only doubt I have is how primo cache handles the video streaming originated by an usb video tuner.

I don't want primo cache write the video streaming to the ssd, because the data is accessed only once.

How can i check if it is actually caching the video stream ?

here the configuration I'm using.
Image

neatchee
Posts: 49
Joined: Tue Feb 12, 2019 8:38 pm

Re: question about video streaming

Post by neatchee » Wed Apr 10, 2019 9:37 pm

It depends on how you have the cache task set up. Click the little button with the platters icon (e.g. next to the dropdown you currently have set to "MAX" in your screenshot) to see advanced options discussed below.

Options:
Read/Write cache with shared space for both
* Writes will hit the cache before being written to disk.
* Any free space in the cache will be used for writes and then persist in the cache.
* At the same time, frequently read data will be loaded into the cache from disk
* Once there's no space left in the cache, standard rules will apply - loosely, the most frequently read/written blocks will be cached

Read/write cache split into separate read and write sections
* Writes will fill the write space only
* Reads will populate the read space only, based on most frequently read blocks

Read-only cache (non-shared, with 100% space reserved for read)
* Writes will go straight to disk, bypassing the cache
* Cache will be populated from the disk based on most frequently read blocks

For your use-case I'd recommend the last option. It will make sure that your TV-tuner writes never hit the cache, and over time only your most frequently read data will fill the cache. The downside is that data you've just written to the drive won't immediately be available in the cache.

I may be slightly off on some of the specific technical behaviors of each scenario above - Jaga or a Romex employee can clarify - but I think I'm pretty close to the actual behavior :)

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support
Posts: 2515
Joined: Sun Dec 21, 2008 2:42 am

Re: question about video streaming

Post by support » Thu Apr 11, 2019 4:18 pm

@tom78, if I understand correctly, you intend to speed up video games by RAM and SSD cache and speed up tv stream recording by L1 only, right? Correct me if I'm wrong. As tv recording is a write behavior to HDD, to speed up writing, you may enable the Defer-Write option. Please see
http://www.romexsoftware.com/en-us/prim ... on.html#dw
By default, L1 (RAM) cache is set to cache both read-data and write-data, and L2 (SSD) cache is set to cache read data only. So tv recording will only be cached by L1 cache and will not be cached by L2 cache. You can change in L1/L2 advanced settings.

@neatchee, your are correct.
Primo Ramdisk | PrimoCache
Romex Software Support

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Jaga
Posts: 419
Joined: Sat Jan 25, 2014 1:11 am

Re: question about video streaming

Post by Jaga » Thu Apr 11, 2019 4:40 pm

tom78 wrote:
Wed Apr 10, 2019 8:20 am
The only doubt I have is how primo cache handles the video streaming originated by an usb video tuner.

I don't want primo cache write the video streaming to the ssd, because the data is accessed only once.

How can i check if it is actually caching the video stream ?

here the configuration I'm using.
Image
If the data is accessed only once, and you don't want it written to the L2 SSD, then there's no reason to cache the data at all. Caching uses either multiple reads or cached writes. The L1 (at 2.8GB) is barely large enough to hold a streamed HD show, so to cache it (if it is only ever read once) would have to happen during the write stage to the L2.

Support is correct in that using deferred writes can help the L1 to speed up the recording stream, but if you don't have a UPS on the computer, it can be risky.

Maybe a little more information on what you are trying to accomplish with your streaming, how you use those shows, if you keep them, if you watch them more than once, etc.. would be helpful.

The other solution would be using Primo RAMdisk, creating a volume in memory to stream shows to that you watch once, and then you either delete them or move them to the 1TB drive.

tom78
Posts: 4
Joined: Wed Apr 10, 2019 7:50 am

Re: question about video streaming

Post by tom78 » Fri Apr 12, 2019 9:28 am

support wrote:
Thu Apr 11, 2019 4:18 pm
@tom78, if I understand correctly, you intend to speed up video games by RAM and SSD cache and speed up tv stream recording by L1 only, right?
Hi support,
thanks for your answer.

I want primo cache speed up the videogames.
I don't want primo cache speed up video streaming (hard disk can deal with the streaming video without issues, and i don't want waste lifespan of my ssd on pointless operations).

Video games are installed on a normal 1 TB hard disk.
On the same hard disk i also configured the tv tuner software to write the streaming video.
I have a dedicated partition for primo cache on my SSD.

I want to be sure i configured primo cache correctly... how i can verify if It is populating the cache with video games data and is skipping video streams ?

What are the best parameters should I use for my needs ? So far I'm using "optimize only reading" default preset, and actually video games are faster to load now.

tom78
Posts: 4
Joined: Wed Apr 10, 2019 7:50 am

Re: question about video streaming

Post by tom78 » Fri Apr 12, 2019 9:30 am

neatchee wrote:
Wed Apr 10, 2019 9:37 pm

For your use-case I'd recommend the last option. It will make sure that your TV-tuner writes never hit the cache, and over time only your most frequently read data will fill the cache. The downside is that data you've just written to the drive won't immediately be available in the cache.
This is actually my current configuration... how can I verify that Primo isn't writing video streaming to the ssd ?

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Jaga
Posts: 419
Joined: Sat Jan 25, 2014 1:11 am

Re: question about video streaming

Post by Jaga » Fri Apr 12, 2019 6:03 pm

tom78 wrote:
Fri Apr 12, 2019 9:28 am
support wrote:
Thu Apr 11, 2019 4:18 pm
@tom78, if I understand correctly, you intend to speed up video games by RAM and SSD cache and speed up tv stream recording by L1 only, right?
Hi support,
thanks for your answer.

I want primo cache speed up the videogames.
I don't want primo cache speed up video streaming (hard disk can deal with the streaming video without issues, and i don't want waste lifespan of my ssd on pointless operations).

Video games are installed on a normal 1 TB hard disk.
On the same hard disk i also configured the tv tuner software to write the streaming video.
I have a dedicated partition for primo cache on my SSD.

I want to be sure i configured primo cache correctly... how i can verify if It is populating the cache with video games data and is skipping video streams ?

What are the best parameters should I use for my needs ? So far I'm using "optimize only reading" default preset, and actually video games are faster to load now.
You should partition your 1TB drive into separate volumes: one for your game installations which you cache with Primocache, and one for your streaming files. You can't separate out what Primocache does/does not cache on the same volume in a cache task.

If you have them both on the same volume and you make it read-only, then save games and such won't be cached when written. Partitioning is the best solution for your needs, in my opinion.

tom78
Posts: 4
Joined: Wed Apr 10, 2019 7:50 am

Re: question about video streaming

Post by tom78 » Fri Apr 12, 2019 10:51 pm

i don't care about writing cache... i don't need it ... repartition 1 tb hard drive isnt' an option .

neatchee
Posts: 49
Joined: Tue Feb 12, 2019 8:38 pm

Re: question about video streaming

Post by neatchee » Sat Apr 13, 2019 1:34 am

tom78 wrote:
Fri Apr 12, 2019 9:30 am
This is actually my current configuration... how can I verify that Primo isn't writing video streaming to the ssd ?
It's quite simple: it can't. If you've specified the cache configuration in the advanced settings as Read-only ("Individual Read/Write Cache Space" with the slider set for 100% Read) then it won't cache writes, period. It'll only fill the cache via the "gather" behavior based on frequently read blocks.

You can kind of verify this by watching the cache task statistics while the TV-tuner is writing to disk; you should see the Total Write (Req) and Total Write (Disk) values increasing while Total Write (L1/L2) stays at 0; meanwhile the L2Storage Write value should not be increasing while the TV-Tuner is writing to disk, only sometimes after you see the Total Read value go up when L2Storage Read doesn't (as that's the Gather behavior filling the cache).

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